The research proposed is aimed at developing a system for growing chick embryo fibroblast (CEF) cells on microcarriers in bioreactors for the large- scale production of avian and human virus vaccines. CEF cells in roller bottles are used to manufacture avian vaccines such as Marek's and Newcastle. Embryonated eggs (CEF) are used to manufacture human vaccines such as influenza. Since both manufacturing processes are labor intensive and subject to process variations, conversion of these processes to a controlled bioreactor environment would result in more consistent and lower cost products. Vaccine recipients who are allergic to egg products will be relieved. The Specific Aims are directed at showing the feasibility with two of our newest microcarrier substrates, which have promise as the preliminary data show. Specific Aim I. To examine (1) primary CEF cells grown on ProNectin F coated microcarriers and (2) trimethylamine core microcarriers for production of the herpesvirus of turkeys (Marek's disease) and compare (3) virus yields obtained with microcarrier-grown cells to yields obtained with cells grown in roller bottles and/or in embryonated eggs. Specific Aim II and III. To conduct experiments utilizing (1) secondary passage CEF cells, (2) an established CEF cell line and (3) custom formulated media. PROPOSED COMMERCIAL APPLICATIONS: At the present time there are huge, and numerous, industrial applications for primary chick embryo fibroblast (CEF) cells. Both animal vaccines (e.g. Marek's) and human vaccines (e.g. influenza) are manufactured using CEF cells, some processes use CEFs in roller bottles, some are in embryonated eggs, but none use CEFs on microcarriers in bioreactors. It would be economically advantageous to all the vaccine manufacturers to be able to reduce labor content by applying CEF cells to microcarriers in bioreactors. This new system we propose, will include CEF cells, microcarriers and the custom media.